1. Field of the Present Invention
The present invention relates generally to a positioning and data integrating method and systems, and more particularly to an improved positioning and data integrating method and system for personal hand-held applications, such as air, land, and water vehicles, which employs integrated global positioning system/inertial measurement unit, enhanced with optional other navigation devices to derive vehicle position, velocity, attitude, and body acceleration and rotation information, and distributes these data to other onboard systems, for example, in the case of aircraft applications, flight management system, flight control system, automatic dependent surveillance, cockpit display, enhanced ground proximity warning system, weather radar, and satellite communication system.
2. Description of Related Arts
There are commonly difficult problems in the integrated design of positioning and data integrating method and systems for personal hand-held applications and various vehicles, including avionics systems for aircraft. Commercial aircraft avionics systems, such as multiple radios, navigation systems, flight management systems, flight control systems, and cockpit display, are ever-increasing in complexity. Each has dedicated controls that require the pilot""s attention, particularly during critical flight conditions. Moreover, the task is compounded when the pilot""s accessibility to dedicated controls is limited by cockpit space restrictions.
Flight management system (FMS) includes flight navigation management, flight planning, and integrated trajectory generator and guidance law. The FMS of a flight vehicle acts in conjunction with the measurement systems and onboard inertial reference systems to navigate the vehicle along trajectory and off trajectory for enroute, terminal, and approach operations. Nowadays, advanced flight vehicles are equipped with flight management computers which calculate trajectories and with integrated control system which fly the vehicle along these trajectories, thus minimizing direct operating cost.
The guidance function is carried out using the FMS. In some applications, the cruise control law and some automatic trajectory tracking control laws (especially for four-dimensional control and lateral turns) are also included in the FMS. In this way, they are closely coupled with the guidance functions. In the approaching and landing phase, the optimal position of the vehicle is captured by the FMS through the calculation of the trajectory. Precise guidance and control are required because the cross-track error and the relative position deviation are sensitive to the accuracy of guidance. Hence, the accuracy of the guidance function in the FMS greatly determines the vehicle performance of approaching and landing as well as other critical mission segments. However, the automatic flight control system (FCS), not the FMS, should include critical functions for both operational and failure considerations because critical functions such as those of high band pass inner-loops are normally handled by an automatic FCS. Therefore, it is desired to avoid incorporating these functions in the FMS even though they can be handled with separate processors in the FMS.
Assuming that the fast control loop is 100 Hz and the slow control loop is 50 Hz, the selection of 50 Hz as the major frame updates the major frame every 20 ms. The sensor input is at 200 Hz. If it is chosen as a minor frame, then the minor frame is 5 ms. Other subsystems at 50 Hz are the guidance command, the FCS data input, the FCS data output, and the actuation/servo command. At each major frame, the sensor inputs are updated four times and the fast control loops are computed twice. The slow control loop, the guidance command, the FCS data input, the FCS data output, and the actuation/servo command are updated once.
The increasing complexity of the flight management systems and flight control systems, as well as other avionics systems, requires the integrated design of avionics or integrated avionics systems. For instance, it is anticipated that the new generation of commercial aircraft will use integrated modular avionics, which will become an integral part of the avionics architecture for these aircraft. The integrated modular avionics suite will enable the integrated avionics to share such functions as processing, input/output, memory, and power supply generation. The flight decks of these new generation of airliners will incorporate advanced features such as flat-panel screens instead of cathode-ray tubes (CRTs), which will display flight, navigation, and engine information.
Advances in inertial sensors, displays, and VLSI/VHSIC (Very Large Scale Integration/Very High Speed Integrated Chip) technologies made possible the use of navigation systems to be designed for commercial aviation aircraft to use all-digital inertial reference systems (IRS). The IRS interfaces with a typical transport aircraft flight management system. The primary outputs from the system are linear accelerations, angular rates, pitch/roll attitude, and north-east-vertical velocity data used for inputs to a transport flight control system.
An inertial navigation system comprises an onboard inertial measurement unit, a processor, and an embedded navigation software. The positioning solution is obtained by numerically solving Newton""s equations of motion using measurements of vehicle specific forces and rotation rates obtained from onboard inertial sensors. The onboard inertial sensors consist of accelerometers and gyros which together with the associated hardware and electronics comprise the inertial measurement unit.
The inertial navigation system may be mechanized in either a gimbaled or strapdown configuration. In a gimbaled inertial navigation system, the accelerometers and gyros are mounted on a gimbaled platform to isolate the sensors from the rotations of the vehicle, and to keep the measurements and navigation calculations in a stabilized navigation coordinated frame. Possible navigation frames include earth centered inertial (ECI), earth-centered-earth-fix (ECEF), locally level with axes in the directions of north, east, down (NED), and locally level with a wander azimuth. In a strapdown inertial navigation system, the inertial sensors are rigidly mounted to the vehicle body frame, and a coordinate frame transformation matrix (analyzing platform) is used to transform the body-expressed acceleration and rotation measurements to a navigation frame to perform the navigation computation in the stabilized navigation frame. Gimbaled inertial navigation systems can be more accurate and easier to calibrate than strapdown inertial navigation systems. Strapdown inertial navigation systems can be subjected to higher dynamic conditions (such as high turn rate maneuvers) which can stress inertial sensor performance. However, with the availability of newer gyros and accelerometers, strapdown inertial navigation systems are becoming the predominant mechanization due to their low cost and reliability.
Inertial navigation systems in principle permit pure autonomous operation and output continuous position, velocity, and attitude data of vehicle after initializing the starting position and initiating an alignment procedure. In addition to autonomous operation, other advantages of inertial navigation system include the full navigation solution and wide bandwidth. However, an inertial navigation system is expensive and subject to drift over an extended period of time. It means that the position error increases with time. This error propagation characteristic is primarily caused by its inertial sensor error sources, such as gyro drift, accelerometer bias, and scale factor errors.
The innovative method and system for integrated design of positioning and data integrating method and systems for an avionics system for aircraft were disclosed in a previous patent application of the application, entitled xe2x80x9cVehicle Positioning and Data Integrating Method and System Thereofxe2x80x9d, application Ser. No. 09/374,480, filed on Aug. 13, 1999. Although it is obvious that the previous application can be applied in both land and water vehicles and other onboard systems for air, land, and water vehicles, it is preferred to provide specific embodiments for how to embody the techniques of the previous application for land and water vehicle applications, as well as personal hand-held applications.
It is a main objective of the present invention to provide an improved positioning and data integrating method and system thereof, in which a control board manages and distributes the navigation data and inertial sensor data to other onboard systems for air, land, and water vehicles.
Another objective of the present invention is to provide an improved positioning and data integrating method and system thereof for hand-held application, wherein a control board manages and distributes the navigation data and inertial sensor data to a display device and wireless communication device.
Another objective of the present invention to provide an improved positioning and data integrating method and system thereof for air, land, and water vehicles, wherein one or more or all of the following devices: altitude measurement device, north finder, velocity producer, terrain data base, and an object detection system interface, are incorporated with a global positioning system/inertial measurement unit integrated navigation system to enhance the position solution and control performance to adapt a variety of applications.
Another objective of the present invention is to provide a universal vehicle positioning and data integrating method and system thereof for air vehicles, in which the flight management system gets vehicle position, velocity, attitude, and time data from a global positioning system/inertial measurement unit integrated navigation system enhanced by an altitude measurement unit to perform flight management operations.
Another objective of the present invention to provide a universal vehicle positioning and data integrating method and system thereof for air vehicles, in which the flight control system gets vehicle attitude and velocity, and vehicle body acceleration and rotation data from a global positioning system/inertial measurement unit integrated navigation system enhanced by an altitude measurement unit to perform vehicle flight control.
Another objective of the present invention to provide a universal vehicle positioning and data integrating method and system thereof for air vehicles, in which the automatic dependent surveillance system gets vehicle position and time data from a global positioning system/inertial measurement unit integrated navigation system enhanced by an altitude measurement unit to report vehicle""s position.
Another objective of the present invention to provide a universal vehicle positioning and data integrating method and system thereof for air vehicles, in which the cockpit display gets vehicle position, attitude, heading, velocity, and time data from a global positioning system/inertial measurement unit integrated navigation system enhanced by an altitude measurement unit to display navigation information.
Another objective of the present invention to provide a universal vehicle positioning and data integrating method and system thereof for air vehicles, in which the enhanced ground proximity warning system gets vehicle position, velocity, and attitude data from a global positioning system/inertial measurement unit integrated navigation system enhanced by an altitude measurement unit to query terrain data, and to predict the transportation path.
Another objective of the present invention to provide a universal vehicle positioning and data integrating method and system thereof for air vehicles, in which the weather radar gets platform attitude and body acceleration data from a global positioning system/inertial measurement unit integrated navigation system enhanced by an altitude measurement unit to stabilize the weather radar antenna.
Another objective of the present invention to provide a universal vehicle positioning and data integrating method and system thereof for air vehicles, in which the satellite communication system gets vehicle position and attitude data from a global positioning system/inertial measurement unit integrated navigation system enhanced by an altitude measurement unit to point the communication antenna to the satellite.
The present invention can substantially solve the problems encountered in avionics system integration by using the state-of-the-art inertial sensor, global positioning system technology, integrated global positioning system/inertial measurement unit enhanced with altitude measurements, and advanced bus and computing technologies. The present invention is to balance multiple requirements imposed on the modern avionics systems design and manufacturing: low cost, high accuracy, reliability, small size and weight, low power consumption, ease of operation and maintenance, and ease of modification.